This invention relates to an improved oxidant and more in particular to an acidic, aqueous, oxidizing agent containing bromate and iodate ions.
Dying of various fabrics to impart a color to the fiber has been practiced for many centuries. The color must generally be permanently and uniformly distributed throughout the fiber and not merely superficially applied to the fiber as in painting. Many different types of natural and regenerated cellulosic fibers have been dyed to impart a color. For example, natural fibers, such as the vegetable fibers cotton, linen, jute, and flax have been dyed. Regenerated cellulosic fibers, such as viscose rayon and cellulose acetate, are those produced from natural materials which were altered by man to produce a desired textile material.
It has become accepted, and common, practice to color these materials with well-known sulfur and vat dyes. These dyes are water insoluble substances which are readily converted to a water soluble or leuco form by reducing the sulfur or vat dye in, for example, a solution containing an alkali and sodium sulfide or hydrosulfite.
The leuco forms of sulfur and vat dyes are water soluble and well known to be substantive to cellulosic fibers. After application to the fiber, the leuco dye must be oxidized to permanently color the fabric. The process of U.S. Pat. No. 3,775,047 oxidized the dye with an aqueous oxidizing solution including acetic acid and sodium or potassium iodate. U.S. Pat. No. 4,042,319 disclosed similar oxidation with an aqueous oxidant containing acetic or formic acid, an alkali bromate and an alkali iodate. Oxidizing of vat of sulfur dyes with an aqueous agent containing either a bromate or an iodate compound and a vanadium compound was described in U.S. Pat. No. 4,012,192. Such oxidizing solutions are operable; however, it is desired to provide an improved material suitable to oxidize leuco forms of sulfur and vat dyes.